// 版权所有2011 Go作者。保留所有权利。
// 此源代码的使用受BSD样式
// 许可证的约束，该许可证可以在许可证文件中找到。

// 此文件设置了宇宙范围和不安全的包。

package types2

import (
	"go/constant"
	"strings"
)

// 宇宙范围包含所有预先声明的Go对象。
// 它是任何嵌套作用域链中最外层的作用域。
var Universe *Scope

// 不安全的包是导入程序返回的包
// 用于导入路径“不安全”。
var Unsafe *Package

var (
	universeIota       Object
	universeByte       Type // uint8别名，但名称为“字节”
	universeRune       Type // int32别名，但名称为“符文”
	universeAny        Object
	universeError      Type
	universeComparable Object
)

// Typ包含按其
// 对应基本索引的预声明*基本类型。
// 
// Typ[Byte]的*基本类型的名称为“uint8”。
// 使用宇宙。查找（“字节”）。Type（）获取特定的
// 别名基本类型，名为“byte”（与“rune”类似）。
var Typ = [...]*Basic{
	Invalid: {Invalid, 0, "invalid type"},

	Bool:          {Bool, IsBoolean, "bool"},
	Int:           {Int, IsInteger, "int"},
	Int8:          {Int8, IsInteger, "int8"},
	Int16:         {Int16, IsInteger, "int16"},
	Int32:         {Int32, IsInteger, "int32"},
	Int64:         {Int64, IsInteger, "int64"},
	Uint:          {Uint, IsInteger | IsUnsigned, "uint"},
	Uint8:         {Uint8, IsInteger | IsUnsigned, "uint8"},
	Uint16:        {Uint16, IsInteger | IsUnsigned, "uint16"},
	Uint32:        {Uint32, IsInteger | IsUnsigned, "uint32"},
	Uint64:        {Uint64, IsInteger | IsUnsigned, "uint64"},
	Uintptr:       {Uintptr, IsInteger | IsUnsigned, "uintptr"},
	Float32:       {Float32, IsFloat, "float32"},
	Float64:       {Float64, IsFloat, "float64"},
	Complex64:     {Complex64, IsComplex, "complex64"},
	Complex128:    {Complex128, IsComplex, "complex128"},
	String:        {String, IsString, "string"},
	UnsafePointer: {UnsafePointer, 0, "Pointer"},

	UntypedBool:    {UntypedBool, IsBoolean | IsUntyped, "untyped bool"},
	UntypedInt:     {UntypedInt, IsInteger | IsUntyped, "untyped int"},
	UntypedRune:    {UntypedRune, IsInteger | IsUntyped, "untyped rune"},
	UntypedFloat:   {UntypedFloat, IsFloat | IsUntyped, "untyped float"},
	UntypedComplex: {UntypedComplex, IsComplex | IsUntyped, "untyped complex"},
	UntypedString:  {UntypedString, IsString | IsUntyped, "untyped string"},
	UntypedNil:     {UntypedNil, IsUntyped, "untyped nil"},
}

var aliases = [...]*Basic{
	{Byte, IsInteger | IsUnsigned, "byte"},
	{Rune, IsInteger, "rune"},
}

func defPredeclaredTypes() {
	for _, t := range Typ {
		def(NewTypeName(nopos, nil, t.name, t))
	}
	for _, t := range aliases {
		def(NewTypeName(nopos, nil, t.name, t))
	}

	// type any=interface{}
	// 注意：不要对any的类型使用&emptyInterface。使用一个唯一的
	// 指针，我们可以检测任何错误，并将其格式化为“any”，而不是
	// 接口{}，这大大澄清了用户面临的错误消息。
	def(NewTypeName(nopos, nil, "any", &Interface{complete: true, tset: &topTypeSet}))

	// 类型错误接口{error（）string}
	{
		obj := NewTypeName(nopos, nil, "error", nil)
		obj.setColor(black)
		typ := NewNamed(obj, nil, nil)

		// 错误。Error（）string 
		recv := NewVar(nopos, nil, "", typ)
		res := NewVar(nopos, nil, "", Typ[String])
		sig := NewSignatureType(recv, nil, nil, nil, NewTuple(res), false)
		err := NewFunc(nopos, nil, "Error", sig)

		// 接口{Error（）string}
		ityp := &Interface{obj: obj, methods: []*Func{err}, complete: true}
		computeInterfaceTypeSet(nil, nopos, ityp) // 防止由于tset 

		typ.SetUnderlying(ityp)
		def(obj)
	}

	// 类型可比接口{}
	{
		obj := NewTypeName(nopos, nil, "comparable", nil)
		obj.setColor(black)
		typ := NewNamed(obj, nil, nil)

		// 接口{}
		ityp := &Interface{obj: obj, complete: true, tset: &_TypeSet{nil, allTermlist, true}}

		typ.SetUnderlying(ityp)
		def(obj)
	}
}

var predeclaredConsts = [...]struct {
	name string
	kind BasicKind
	val  constant.Value
}{
	{"true", UntypedBool, constant.MakeBool(true)},
	{"false", UntypedBool, constant.MakeBool(false)},
	{"iota", UntypedInt, constant.MakeInt64(0)},
}

func defPredeclaredConsts() {
	for _, c := range predeclaredConsts {
		def(NewConst(nopos, nil, c.name, Typ[c.kind], c.val))
	}
}

func defPredeclaredNil() {
	def(&Nil{object{name: "nil", typ: Typ[UntypedNil], color_: black}})
}

// 内置id是内置函数的id。
type builtinId int

const (
	// 宇宙范围
	_Append builtinId = iota
	_Cap
	_Close
	_Complex
	_Copy
	_Delete
	_Imag
	_Len
	_Make
	_New
	_Panic
	_Print
	_Println
	_Real
	_Recover

	// 包不安全
	_Add
	_Alignof
	_Offsetof
	_Sizeof
	_Slice

	// 测试支持
	_Assert
	_Trace
)

var predeclaredFuncs = [...]struct {
	name     string
	nargs    int
	variadic bool
	kind     exprKind
}{
	_Append:  {"append", 1, true, expression},
	_Cap:     {"cap", 1, false, expression},
	_Close:   {"close", 1, false, statement},
	_Complex: {"complex", 2, false, expression},
	_Copy:    {"copy", 2, false, statement},
	_Delete:  {"delete", 2, false, statement},
	_Imag:    {"imag", 1, false, expression},
	_Len:     {"len", 1, false, expression},
	_Make:    {"make", 1, true, expression},
	_New:     {"new", 1, false, expression},
	_Panic:   {"panic", 1, false, statement},
	_Print:   {"print", 0, true, statement},
	_Println: {"println", 0, true, statement},
	_Real:    {"real", 1, false, expression},
	_Recover: {"recover", 0, false, statement},

	_Add:      {"Add", 2, false, expression},
	_Alignof:  {"Alignof", 1, false, expression},
	_Offsetof: {"Offsetof", 1, false, expression},
	_Sizeof:   {"Sizeof", 1, false, expression},
	_Slice:    {"Slice", 2, false, expression},

	_Assert: {"assert", 1, false, statement},
	_Trace:  {"trace", 0, true, statement},
}

func defPredeclaredFuncs() {
	for i := range predeclaredFuncs {
		id := builtinId(i)
		if id == _Assert || id == _Trace {
			continue // 仅在测试环境中定义这些
		}
		def(newBuiltin(id))
	}
}

// DefPredeclaredTestFuncs定义断言和跟踪内置。
// 这些内置程序仅用于调试和测试此
// 软件包。
func DefPredeclaredTestFuncs() {
	if Universe.Lookup("assert") != nil {
		return // 已定义
	}
	def(newBuiltin(_Assert))
	def(newBuiltin(_Trace))
}

func init() {
	Universe = NewScope(nil, nopos, nopos, "universe")
	Unsafe = NewPackage("unsafe", "unsafe")
	Unsafe.complete = true

	defPredeclaredTypes()
	defPredeclaredConsts()
	defPredeclaredNil()
	defPredeclaredFuncs()

	universeIota = Universe.Lookup("iota")
	universeByte = Universe.Lookup("byte").Type()
	universeRune = Universe.Lookup("rune").Type()
	universeAny = Universe.Lookup("any")
	universeError = Universe.Lookup("error").Type()
	universeComparable = Universe.Lookup("comparable")
}

// 名称包含空格的对象是内部对象，未输入
// 范围。带有导出名称的对象被插入到不安全的包
// scope中；其他对象插入到宇宙范围中。
// 
func def(obj Object) {
	assert(obj.color() == black)
	name := obj.Name()
	if strings.Contains(name, " ") {
		return // 无需执行
	}
	// 修复命名类型的Obj链接
	if typ, _ := obj.Type().(*Named); typ != nil {
		typ.obj = obj.(*TypeName)
	}
	// 导出的标识符进入包不安全
	scope := Universe
	if obj.Exported() {
		scope = Unsafe.scope
		// 设置包字段
		switch obj := obj.(type) {
		case *TypeName:
			obj.pkg = Unsafe
		case *Builtin:
			obj.pkg = Unsafe
		default:
			unreachable()
		}
	}
	if scope.Insert(obj) != nil {
		panic("double declaration of predeclared identifier")
	}
}
